Battery-powered hand-guided power tool

ABSTRACT

A battery-powered hand-guided power tool is provided, such as a hammer, includes a tool housing  3  that contains an electric motor M, a grip housing  2  and a rail-and-channel structure  36, 37, 54, 55  for releasable mounting of a rechargeable battery pack  50 . The battery pack  50  is locked in an operative position on the housing  3  in which electrical contacts ( 51 ) of the battery pack  50  and associated electrical contacts  42  of the tool housing are electrically connected along a contact length extending in a longitudinal direction of the rail-and-channel arrangement. A latch structure  18,19  located on the tool housing  3  is movable between a latched position and a release position. When the latch structure  18,19  is moved from the latched position into the release position, the battery pack  50  can be moved in the direction of the longitudinal extent of the rail-and-channel structure  36, 37, 54, 55  out of the operative position and can be removed from the tool housing  3 . Between the battery pack  50  and the tool housing  3  there is arranged a spring  38  which loads the inserted battery pack  50  in a direction of a displacement movement out of the operative position. The distance of travel of the spring  38  is greater than the contact length of the contacts  42,51  and the restoring force of the spring  38  at the contact length is greater than the weight of the battery pack  50.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a battery-powered, hand-guided powertool, and in particular to a hammer, in which a rechargeable batterypack is releasably connected to a tool housing of the hammer via arail-and-channel structure, and the battery pack is locked in anoperative position on the tool housing in which electrical contacts ofthe battery pack and associated electrical contacts of the power toolare electrically connected along a contact length extending in thedirection of a longitudinal extent of the rail-and-channel structure.

[0002] A power tool, such as a drilling hammer, is disclosed in GermanPatent Publication No. DE 195 21 423 (A1) and includes a tool housing.The tool further includes a rail-and-channel structure which is formedon a side portion of the tool housing and extends on a front side of aportion of the housing. The tool housing is also formed with a rear handgrip substantially at right angles to a longitudinal axis of a toolholder supported at the front of the tool. A spring-loaded latch elementis located in a lower part of the hand grip, which, when in a lockingposition and with a battery housing assembled with the tool housing,engages in a latch recess of the battery housing to thus hold thebattery pack in its operative position on the tool housing. The latchelement is accessible through an opening at the lower end of the handgrip, so that a user may move the latch element, manually against theforce of a compression spring, out of the locking position and into arelease position.

[0003] With structure disclosed in German Patent Application No. DE 19521 423, a user has to hold the power tool with one hand and use theother hand to move the latch element into a release position to releasethe battery pack. If, in so doing, the user has oriented the power toolso that the battery pack is able to come free of the power tool undergravity, there is a risk that the battery pack, which the user is unableto hold at the same time, will drop out in an uncontrolled manner, whichcan lead to damage to the battery pack and perhaps even to injury. If,on the other hand, the user holds the power tool oriented so that, asthe latch element is displaced, the battery pack is supported on theportion of the housing forming the hand grip, that is, with the toolholder axis directed upwardly, the battery pack will not move from itsposition as the latch element is drawn back. When the latch element issubsequently released, it will again enter the latch recess of thebattery pack, so that the battery pack continues to be connected to thepower tool.

[0004] Also, with the structure disclosed in German Patent ApplicationNo. DE 195 21 423, if the user inserts the battery pack in the lastposition mentioned, the electrical contacts of the power tool and thebattery pack may come into contact, but the latch element may,unnoticed, fail to lock in the latch recess. Although the power tool canbe operated in this position, the battery pack will suddenly becomedetached from the power tool when this is inclined at a relevant angle,the surprise effect in particular of such an occurrence possibly leadingto injury to the user or even to other persons, for instance, if thepower tool is being used on a construction site.

SUMMARY OF THE INVENTION

[0005] Therefore, it is an object of this invention to construct a powertool such that, with greater safety in use, the battery pack can bemoved in a simple manner out of its operative position.

[0006] With this and other objects in mind, this invention contemplatesa battery-powered, hand-guided power tool in which a rechargeablebattery pack is releasably connected to a tool housing. Arail-and-channel structure is formed with a longitudinal extent betweenopposite ends thereof, for facilitating the assembly of the battery packin an operative position on the tool housing. A locking device,including a latch structure, is located on the housing for locking thebattery pack with the housing in the operative position, and includes alatch structure which is locatable between a device latched position,coincidental with the operative position of the battery pack, and adevice release position. A plurality of electrical battery contacts arelocated on the battery pack, and a plurality of electrical tool contactsare located on the tool housing. The battery contacts and the toolcontacts have a prescribed contact length along which they electricallyengage. The battery contacts and the tool contacts extend in a directionalong the longitudinal extent of the rail-and-channel structure, and areelectrically connected when the battery pack in is the operativeposition. The battery pack is movable from the operative position into abattery release position when the latch structure is moved from thedevice latched position to the device release position to permit thebattery pack to be moved in the direction of the longitudinal extent ofthe rail-and-channel structure for removal from the tool housing. Aspring is located on the tool housing and positioned to apply aspring-loaded force to the battery pack in the operative position in adirection of a displacement movement of the battery pack out of theoperative position. The spring is expandable by a distance greater thanthe prescribed contact length, and the restoring force of the springwhen extended to the prescribed contact length is greater than theweight of the battery pack.

[0007] Other objects, features and advantages of the present inventionwill become more fully apparent from the following detailed descriptionof the preferred embodiment, the appended claims and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In the accompanying drawings:

[0009]FIG. 1 is side view showing a drilling hammer with battery packlocated in its operative position in accordance with certain principlesof the invention;

[0010]FIG. 2 is a partial perspective view showing a battery pack inassembly with parts of the drilling hammer of FIG. 1 in accordance withcertain principles of the invention;

[0011]FIG. 3 is a sectional view taken along line III-III of FIG. 1through tool housing of the drilling hammer, but with the omission ofthe parts of motor and gear structure normally present in this region,in accordance with certain principles of the invention;

[0012]FIG. 4 is an exploded perspective view showing the tool housing,with parts to be assembled therewith, and the battery pack, inaccordance with certain principles of the invention;;

[0013]FIG. 5 is an exploded perspective view showing the tool housing,with parts to be assembled therewith, in accordance with certainprinciples of the invention;

[0014]FIG. 6 is a partial perspective view showing a portion of one halfshell of a grip housing of the drilling hammer od FIG. 1, a half shellof the housing of the battery pack used and parts of the motor housingin accordance with certain principles of the invention;

[0015]FIG. 7 is a partial perspective view showing the engagement of thetool-side contacts and the battery-side contacts when the battery packis locked in its operative position according to certain principles ofthe invention;

[0016]FIG. 8 is a side view showing the drilling hammer of FIG. 1 withan unlocked battery pack;

[0017]FIG. 9 is a partial perspective view, corresponding to FIG. 2,showing the battery pack unlocked;

[0018]FIG. 10 is a partial perspective view, corresponding to FIG. 6,showing the battery pack unlocked; and

[0019]FIG. 11 is a partial perspective view, corresponding to FIG. 7,showing the position of the tool-side contacts and the battery-sidecontacts with the battery pack unlocked.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0020] A power tool, such as a drilling hammer illustrated in FIG. 1,has a tool housing 3, which includes a barrel-like motor housing 1, opentowards a rear end, and further includes, at the rear end, a griphousing 2 formed by two half-shells (one shown). An electric motor M anda pneumatic hammer mechanism (not shown) are normally located in thetool housing 3. A tool holder 7 is fixed in the customary manner on aspindle, not shown) at a front end of the drilling hammer. A hammer bit(not shown), can be inserted in the tool holder 7 and, in the operationcustomary for drilling hammers, is loaded by impacts from the hammermechanism and/or is rotatably driven.

[0021] The grip housing 2 forms a grip opening 4, into which a switchactuator 5 for activating the electric motor extends. The motor ispowered by a battery pack 50, which is detachably secured to thedrilling hammer in a manner to be described hereinafter.

[0022] As shown in FIGS. 3, 4 and 5, the motor housing 1 has anintegrally formed frame part 15 on its underside, which at its rearregion has integrally formed connecting sleeves 14 and in its frontregion has two frame-part recesses 16, 17 that are separated by atransverse wall that lies in the central plane 43 (FIG. 3) of the toolhousing 3, wherein a longitudinal axis 6 of the tool housing coincideswith an axis of rotation of the tool holder 7.

[0023] Compression springs 20, 21 and latch elements 18, 19 are insertedinto respective ones of the frame-part recesses 16, 17, which are in theform of blind bores. In the outer side walls of the recesses 16, 17there are respective slit shaped through openings 44, 45. Into each ofthese through openings 44,45 extends an inner arm 26, 27 respectively ofan operating element 22, 23, respectively, which operating element is inthe form of a substantially L shaped two armed lever and, formedintegrally therewith, is a respective front pivot pin 28, 29 and arespective rear pivot pin 30, 31. The pivot pins 26, 28 and 29, 31 aresnapped into front and rear bearing sleeves 32, 34 and 33, 35respectively, integrally formed with the frame part 15 and open towardsthe outside, so that the operating element 22, 23 is pivotally mountedon the frame part.

[0024] Secured laterally to the frame 15 are covers 8, 9, which have arespective through opening 10, 11 into which the respective outer arm24, 25 of the respective operating element 22, 23 extends, so that theouter face of that arm 24, 25 is accessible from the outside of thecovers. The covers 8, 9 have inwardly projecting, internally threadedconnecting sockets 12, 13, which in the mounted state extend into theconnecting sleeves 14. By means of screws (not shown), internal threadsof the connecting sockets 12,13, the covers 8, 9 are releasably held onthe frame part 15, and they cover in particular the pivot pins 28, 30,and 29, 31 of the operating-elements 22, 23, respectively, and theassociated bearing sleeves 32, 34 and 33, 35, respectively, andconstitute a visual downward continuation of the motor housing 1.

[0025] It will be noted that, by means of this construction, the latchelements 18, 19 form a locking device having a latch structure which canbe very easily mounted and held within the recesses 16, 17. If thespring 20,21 and the associated latch element 18,19 is inserted into theframe-part recess 16,17, then, with the latch element fixedly held, theinner arm 26, 27 of the associated operating element 22, 23 is pushedthrough the respective slit shaped through opening 44, 45 in the sidewall of the respective recess 16, 17 and into a lateral slit shapedopening 18 a,19 a of the respective latch element 18, 19. Thisarrangement prevents the compression spring 20, 21 from being able topush its associated latch element 18, 19 out of the recess 16, 17,respectively.

[0026] The pivot pins 28, 30 and 29, 31 of the operating element 22, 23,respectively, are snapped into the bearing sleeves 32, 34 and 33, 35respectively, so that the operating elements 22, 23 are positioned inthe position shown in FIG. 3 for the operating element 23. As assembled,the compression spring 20 (FIG. 4), presses the latch element 19downward toward the battery pack 50 and against the inner arm 27 of theoperating element 23 as the arm extends into the opening in the latchelement 19, so that the operating element 23 is biassed, causing it topivot clockwise. This pivoting movement is limited by contact of theinner arm 27 against the lower edge of the slit shaped through opening45 provided in the frame part 15, that is, the latch element 19 is ableto protrude downwards out of the recess 17 only as far as the loweredlatched position illustrated in FIG. 3. The same applies to the latchelement 18, not illustrated in FIG. 3, which is inserted in the recess16 and cooperates with the operating element 22.

[0027] At their lower ends, the covers 8, 9 form inwardly projectingrails 36, 37 which extend at least approximately parallel to thelongitudinal axis 6, and which serve as guide and retaining rails forassembling and mounting the battery pack 50. The battery pack 50 isformed with channels 54, 55 of complementary form to the rails 36,37,and are open at the rear end. This allows the front ends of the rails36, 37 to enter the channels 54, 55 and the battery pack 50 to be pushedalong the rails to an end position in which, as shown in FIGS. 1 and 2,the rear wall of the battery pack lies against a front surface formed bythe two half shells of the grip housing 2. The latch elements 18,19 areformed with wedge-shaped surfaces 18 b,19 b at their lower ends. As thebattery pack 50 is assembled with the tool housing 3, upper surfaces ofeach of the latch elements 18,19 engage and compress the compressionsprings 20,21, fully into the recesses 16, 17. In the fully mountedposition of the battery pack 50, as shown in FIG. 6, the latch elements18, 19 snap into latch recesses 52, 53 formed in an upper surface of thebattery pack and lock the battery pack against forward displacement fromthis operative or fully mounted position. In this manner, the rails36,37 and the channels 54,55, respectively, form a rail-and-channelstructure of the drilling hammer for releasably mounting the batterypack 50 with the hammer.

[0028] Thus, the locking device is located on the tool housing 3 forlocking the battery pack 50 with the housing in a battery-pack operativeposition. The locking device includes a latch structure, formed by thelatch elements 18,19, which is locatable between a device latchedposition, coincidental with the operative position of the battery pack,and a device release position.

[0029] As shown in FIGS. 2, 6, 7, 9, 10 and 11, a plurality of toolcontacts 42 are attached to the motor housing 1, and are electricallyconnected via connections to the different components within the toolhousing 3. The tool contacts 42 are arranged in a frame which openstowards the front. A corresponding plurality of battery contacts 51 arelocated on the upper side of the battery pack 50 in the rear regionthereof, and are mounted in a frame which is open at the rear. In theposition shown in FIGS. 2, 6 and 7, that is, the locked or operativeposition of the battery pack 50, the battery contacts 51 are inelectrically conducting engagement with the tool contacts 42.

[0030] As shown in FIG. 6, an aperture 40 is formed in an upper endregion of the bearing surface of the tool housing 3, which is a bearingsurface for the rear end face of the battery pack 50. A generallythimble shaped cap 39 extends into the aperture 40, and has at its rearend an outwardly directed shoulder, the external diameter of which islarger than the diameter of the aperture 40, so that the cap 39 isunable to escape from the housing through the aperture 40. The cap 39 isbiassed by a helical spring 38, which is located on a supporting pin 41(FIG. 10) formed integrally with the wall of the grip housing 2 oppositethe aperture 40. The helical spring 38 bears against this wall of thegrip housing 2 to effect a forward displacement of the cap 39, that is,to effect a displacement towards a position in which the shoulder of thecap 39 bears against the wall region surrounding the aperture 40. Asshown in FIG. 6, with the battery pack 50 inserted and located in thelocked or operative position, the cap 39 is pushed as far as possibleinto the tool housing 3 with the helical spring 38 fully compressed.

[0031] In order to separate the battery pack 50 in its operativeposition from the drilling hammer, a user grips the covers 8, 9 and thefront region of the battery pack 50 with one hand from the front, andpresses inward, for instance with a thumb and forefinger, the outer arms24, 25 of the operating elements 22 and 23. This causes the operatingelements 22,23 to pivot about their pivot pins 28, 30 and 29, 31,respectively, whereby the latch elements 18, 19 are lifted, against theforce of the compression springs 20, 21, that is, they are moved furtherinto the recesses 16, 17, until the lower ends of the latch elements 18,19 are retracted from the latch recesses 52, 53 of the battery pack 50.As the latch elements 18, 19 release the battery pack 50, the batterypack is urged by the force of the helical spring 38, which presses thecap 39 against the battery pack, forwardly along the rails 36, 37. Aslight displacement of the battery pack 50 is sufficient to ensure thatthe latch elements 18, 19 do not re-enter the latch recesses 52, 53 ofthe battery pack 50 after the operating elements 22, 23 have beenreleased. Instead the latch elements 18,19 abut the upper surface of thebattery pack 50. The helical spring 38 not only effects the slightdisplacement of the battery pack 50, but on release or retraction of thelatch elements 18, 19, the helical spring 38 also urges the battery packsuch a distance along the rails 36 and 37 for a distance sufficient tosafely disengage the battery contacts 51 from the tool contacts 42.

[0032] Accordingly, the displacement of the battery pack 50 by thehelical spring 38 effects not only a mechanical disengagement of thebattery pack, but also causes the electrical connection between thebattery pack and the drilling hammer to be safety interrupted. For thatpurpose, the spring 38 has a restoring force that is greater than theweight of the battery pack 50, so that a corresponding displacement ofthe battery pack can be reliably effected. Thus, even when the userunlocks the battery pack 50 with the tool holder 7 of the power toolpointed upward the battery pack is moved by the spring 38 againstgravity along the vertically positioned rails 36, 37. Moreover, thetravel of the spring 38 between the fully compressed position (FIG. 6)and the position in which the outwardly directed shoulder of the cap 39is supported against the wall region of the tool housing 3 surroundingthe aperture 40 (FIG. 10), is greater than the length over which thebattery contacts 51 in the operative position of the battery pack 50shown in FIGS. 1, 2 and 6 are in engagement with the tool contacts 42.As the latch elements 18, 19 are displaced from the locked positionshown in FIG. 6 into the release position shown in FIG. 10, in anyorientation of the power tool the spring 38 reliably effects adisplacement of the battery pack 50 along the rails 36, 37, such that aseparation of the battery contacts 51 and the tool contacts 42 iseffected.

[0033] For the rest, the travel of the spring 38 between the fullycompressed position (FIG. 6) and the position shown in FIG. 10, in whichthe outwardly directed shoulder of the cap 39 rests against the wallregion surrounding the aperture 40, should not be so large that thebattery pack 50 is moved into a position in which it is no longerreliably held on the rails 36, 37, but is virtually “shot out” of itsmounting on the rails. It is therefore advantageous if the travel orexpandability of the spring 38 is no greater than half the length of thebattery pack 50 in the region of the rail-and-channel structure 36, 37,54, 55 in the direction of the longitudinal extent of the channels 54,55, so that, in the state displaced by the spring 38, the battery packstill rests on at least half the longitudinal extent of the rails 36,37.

[0034] When the user inserts the battery pack 50 into the drillinghammer, the user must move the battery pack sufficiently to displace thecap 39 a distance sufficient to compress the spring 38 to allow thebattery pack to be moved into the position in which the latch elements18, 19 lock into the latch recesses 52, 53 of the battery pack. In thatposition, the battery contacts 51 are then also electrically connectedto the tool contacts 42. If, however, the user fails to push in thebattery pack 50 until the latch elements 18,19 lock in, on beingreleased the battery pack will be displaced by the action of the spring38 into the position shown in FIGS. 8 and 10, so that this error isobvious to the user. Moreover, there is no chance whatsoever that thebattery pack 50 can be electrically connected with the drilling hammerand can set this in operation when the battery pack is not locked in itsoperative position by engagement of the latch elements 18, 19.

[0035] The battery contacts 51 and the tool contacts 42 have aprescribed contact length, along which they electrically engage, andextend in a direction along the longitudinal extent of therail-and-channel structure 36, 37, 54, 55. To insure that the contacts42 and 51 are not accidentally engaged when the battery pack 50 is notfully locked into position on the tool housing 3, the travel orexpandability of the spring 38 is greater than the prescribed contactlength to urge the battery pack sufficiently away from its operativeposition on the tool housing to preclude engagement between thecontacts.

[0036] In general, the above-identified embodiments are not to beconstrued as limiting the breadth of the present invention.Modifications, and other alternative constructions, will be apparentwhich are within the spirit and scope of the invention as defined in theappended claims.

What is claimed is:
 1. A battery-powered, hand-guided power tool inwhich a rechargeable battery pack is releasably connected, whichcomprises: a tool housing; a rail-and-channel structure formed with alongitudinal extent between opposite ends thereof, for facilitating theassembly of the battery pack in an operative position on the toolhousing; a locking device located on the tool housing for locking thebattery pack with the housing in the operative position, and including alatch structure which is locatable between a device-latched position,coincidental with the operative position of the battery pack, and adevice-release position; a plurality of electrical battery contactslocated on the battery pack; a plurality of electrical tool contactslocated on the tool housing; the battery contacts and the tool contactshaving a prescribed contact length along which they electrically engage;the battery contacts and the tool contacts extending in a directionalong the longitudinal extent of the rail-and-channel structure, andbeing electrically connected when the battery pack is in the operativeposition; the battery pack being movable from the operative positioninto a battery release position when the latch structure is moved fromthe device- latched position to the device-release position to permitthe battery pack to be moved in the direction of the longitudinal extentof the rail-and-channel structure for removal from the tool housing; aspring located on the tool housing and positioned to apply aspring-loaded force to the battery pack in the operative position in adirection of a displacement movement of the battery pack out of theoperative position; and the spring being expandable by a distancegreater than the prescribed contact length, and the restoring force ofthe spring when extended to the prescribed contact length being greaterthan the weight of the battery pack.
 2. A power tool according to claim1 , wherein the spring can be expanded by a distance no greater thanhalf the length of the battery pack adjacent the rail-and-channelstructure in the direction of the longitudinal extent thereof.
 3. Apower tool according to claim 1 , wherein the latch structure comprisestwo operating elements arranged on opposite sides of a central planecontaining a longitudinal axis of the tool housing.
 4. A power toolaccording to claim 1 , wherein the rail-and-channel structure includesrails which extend at least approximately parallel to a longitudinalaxis of a tool holder of the power tool and is located forward of a griphousing of the power housing which extends away from the longitudinalaxis of the tool holder, and the spring is mounted at a forward side ofthe grip housing.
 5. A power tool according to claim 4 , wherein thespring is a helical spring having a cap on one end extending through anopening in a wall of the grip housing and has an outwardly directedshoulder which engages an inside wall portion of the grip housingadjacent the opening.